Don't auto boot into fastboot by default for USB boot

The factory software uses usb boot for booting into Linux
so don't boot into fastboot by default. When fastboot is
needed the scripts call that explicitely.

Change-Id: I35e7195b477d621e6f37ef24418be857212dda37
diff --git a/common/autoboot.c b/common/autoboot.c
index 85f5765..9c7aca9 100644
--- a/common/autoboot.c
+++ b/common/autoboot.c
@@ -309,7 +309,6 @@
 				 mfgtools\n", 0);
 	} else if (is_boot_from_usb()) {
 		printf("Boot from USB for uuu\n");
-		env_set("bootcmd", "fastboot 0");
 	} else {
 		printf("Normal Boot\n");
 	}